An actuator unit is applied to joints, each movable along two or more axes, such as a hip joint, a knee joint, or an ankle joint of a legged mobile robot. All the moving portions of a power-supply and control-signal harness are accommodated inside the actuator unit, and an electric contact of the actuator unit is on the free end of an output shaft so that a multi-axis robot is easily achieved. The actuator unit has two orthogonal shafts, and is useful to robots having various kinds of joint structures.